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Date: Thu, 04 Jul 2013 13:36:54 +0100
From: pat <g4gvw@aol.com>
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CC: Graham <g8fzk@g8fzk.fsnet.co.uk>
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 Content preview:  Isn't it also true that for any given signal and noise field
    there will be an optimum antenna positioning and orientation that will achieve
    the best obtainable s/n. There is, likewise. an antenna configuration that
    will produce an optimum result. This probably says that the optimum situation
    is found by experimentation and "rules" may always have their exceptions.
    [...] 
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Subject: Re: LF: VK1OD's analysis of the MiniWhip antenna
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Isn't it also true that for any given signal and noise field there will=20
be an optimum antenna positioning and orientation that will achieve the=20
best obtainable s/n. There is, likewise. an antenna configuration that=20
will produce an optimum result. This probably says that the optimum=20
situation is found by experimentation and "rules" may always have their=20
exceptions.

73


On 04/07/13 12:32, Graham wrote:
> G2AVJ*    asserted that  Maxwell    had  slightly over cooked things =20
> and there  where  no E and H  fields  , only vector  potentials  ,=20
> may  be the mini-probe  is a near field array , as its  certainly  not=20
> big  enough  for any other  concept ?
>
> As  for  big Ae's  .that's  really   only  down  to  location, in open=20
> space  , then  a  1 mile  wire Ae will  produce  some  very low  s/n=20
> levels  , in a urban setting , nothing  but  volts  of noise , its=20
> true  a small  probe  can be  located  in a low noise position , but=20
> this  is  the geometry  of the  noise distribution  , not the  Ae  itse=
lf
>
> 73 -G..
>
>
> * Silent Key now
>
> --------------------------------------------------
> From: "Stefan Sch=E4fer" <Stefan.Schaefer@iup.uni-heidelberg.de>
> Sent: Wednesday, July 03, 2013 10:33 PM
> To: <rsgb_lf_group@blacksheep.org>
> Subject: Re: LF: VK1OD's analysis of the MiniWhip antenna
>
>> Wow, thanks.
>> This can lead to a lively discussion :-)
>>
>> I think there are some misunderstandings by VK1OD. He states that=20
>> Roelof says that:  "noise is mainly magnetic". But Roelof means the=20
>> local noise and not the far field noise, e.g. from thunderstorms.=20
>> That is the difference! The local noise H fields pass the walls=20
>> rather than the E fields, in many constellations like urban areas.
>> Furthermore there can be a significant advantage in the obtainable=20
>> SNR compared to a "big" antenna because that small whip antenna can=20
>> be lifted easily by several meters above ground, without having a=20
>> high wind load. A big antenna with a feed point at ground level and a=20
>> few meters near the house may catch a lot of local noise.
>>
>> For me, here on the institutes roof, the small whip antenna=20
>> (https://dl.dropboxusercontent.com/u/19882028/MF/LFMFprobe.JPG)=20
>> achieved MUCH better results than the 70m long wire=20
>> (https://dl.dropboxusercontent.com/u/19882028/LF/IUP%20Antenne_resize.=
jpg)...
>>
>> 73, Stefan/DK7FC
>>
>> Am 03.07.2013 01:02, schrieb Dimitrios Tsifakis:
>>> Hello group,
>>>
>>> here is a web page written by Owen, VK1OD with an analysis of how
>>> PA0RDT's Miniwhip antenna works:
>>>
>>> http://vk1od.net/antenna/PA0RDT-MiniWhip/index.htm
>>>
>>> You may find this interesting.
>>>
>>> 73, Dimitris VK1SV
>>>
>>
>


--=20
73 de pat g4gvw
es gd dx
qth nr Felixstowe
East Coast UK